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A major current challenge in bioorganic chemistry is the identification of effective mimics of protein secondary structures that act as inhibitors of protein–protein interactions (PPIs). In this work, trans‐2‐aminocyclobutanecarboxylic acid (tACBC) was used as the key β‐amino acid component in the design of α/β/γ‐peptides to structurally mimic a native α‐helix. Suitably functionalized α/β/γ‐peptides assume an α‐helix‐mimicking 12,13‐helix conformation in solution, exhibit enhanced proteolytic stability in comparison to the wild‐type α‐peptide parent sequence from which they are derived, and act as selective inhibitors of the p53/hDM2 interaction.

Preparation of bis(2,4,6‐trimethylpyridine)iodine(I) hexafluorophosphate and bis(2,4,6‐trimethylpyridine) bromine(I) hexafluorophosphate intermediate: Bis(2,4,6‐trimethylpyridine)silver(I) hexafluorophosphate product: bis(2,4,6‐trimethylpyridine)iodine(I) hexafluorophosphate product: bis(2,4,6‐trimethylpyridine)bromine(I) hexafluorophosphate

A bottom-up design rationale was adopted to devise β/γ-peptide foldamer manifolds which would adopt preferred 13-helix conformations, relying on minimal steric imposition brought by the constituent amino acid residues. In this way, a well-defined 13-helix conformer was revealed for short oligomers of trans-2-aminocyclobutanecarboxylic acid and γ(4)-amino acids in alternation, which gave good topological superposition upon an α-helix motif.

Enantioselective lactonization of 4‐substituted but‐3‐enoic acids using iodobis(N‐methylephedrine) hexafluoroantimonate in dichloromethane at low temperatures is reported. The presence of bis(N‐methylephedrine)silver(I) hexafluoroantimonate, derived from the excess amounts of N‐methylephedrine and silver hexafluoroantimonate that were necessary for the generation of the iodo complex in the reaction mixture, is crucial for the success of this reaction. The different parameters of these cyclization reactions have been examined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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In addition to the classical N–H···O=C non-covalent interaction, less conventional types of hydrogen bonding, such as N–H···S, may play a key role in determining the molecular structure. In this work,...